To determine when the rate of yield first equals the 10-year average annual yield during the first 10 years, we would typically need specific data regarding the yields for each of those years.

If you provide the yield values for each of the 10 years, I can help calculate the average yield and identify the first instance where the yield equals this average.

If you have a specific dataset or formula, please share it, and I'll assist you further!

Here are some follow-up questions to consider:

1. What are the yield values for each of the 10 years?
2. Are there any trends or patterns in the yield data?
3. How is the yield calculated each year?
4. Is there a specific method used to determine the average?
5. Do you need a detailed explanation of how to calculate the average yield?

Tip: When dealing with averages, make sure to include all relevant data points to avoid skewed results.